Blood Drying Process

Fresh raw blood is pumped from the killing floor to a raw blood holding tank. Approximately an hour after the start of the kill sufficient blood has been collected to start the coagulation and drying process.

Blood is pumped at a constant rate from the holding tank into the coagulator where it is mixed with saturated steam and raised to 180 – 200 Deg. F in a continuous process. It then is centrifuged and obtains a moisture content of approximately 60%. In this state it is a coarse wet powder and is fed directly into the blood dryer.

The blood dryer includes a rotary drum into which the blood is introduced and where it is brought in direct contact with a hot air stream from a direct fired air heater. The hot air stream dries and conveys the product in a concurrent process. The drum is equipped with longitudinal lifting flights which repeatedly drop the product into the axial air stream. Dwell time is approximately 15 minutes. Then the product exits the drum at an outlet moisture of approximately 8%. The outlet moisture is obtained by controlling the drum outlet air temperature and modulating the fuel control system as required.

Heat transfer in the drum is mainly by convection so that the product temperature rises slightly above the wet bulb temperature of the drying gases (approximately 160 Deg. F) resulting in blood meal of flash dried quality.

From the rotating drum the dried blood is conveyed into the primary cyclone where approximately 99.8% of the product is separated from the air stream and discharged through a rotary airlock. The air with the remaining dust is drawn into our Heliclone Separator which is a combination air mover/skimmer. The skimmed off dust with approximately 15% of the air flow is directed into the secondary cyclone where the collected dust is discharged through a rotary airlock. The air flow is returned to the primary cyclone and is thus recycled.